textproduct: Rapid City

KEY MESSAGES

- Active pattern persists through mid-week with daily chances of storms, some of which may be strong to severe.

- Trending warmer to end the week into next weekend.

UPDATE

Issued at 1005 PM MDT Sun Aug 16 2026

Storms have mostly cleared the CWA, heading into Nebraska and central SD. The rest of the night should be quiet...except could see a stray shower across far south central SD overnight. A weak cold front/dry line will push into the CWA on Monday. Best instability will be ahead of the front mainly from the I-90 corridor southward. There is enough shear for some strong/severe storms with large hail/damaging winds. Highs Monday will be in the 80s. An upper wave is then expected to cross the CWA Monday night, bringing late evening and overnight showers/isolated storms.

DISCUSSION

(This Afternoon Through Saturday) Issued at 1129 AM MDT Sun Aug 16 2026

Upper level analysis shows zonal flow across the Northern Plains this morning with subtle embedded shortwaves upstream. Upper ridge is building over the SW US with weak height rises over the area and generally limited upper level ascent. Diffuse surface high pressure is centered over central SD/ND with southeasterly surface flow across the area.

Isolated to scattered thunderstorms are expected this afternoon across the area despite the weak upper level forcing. Forecast MLCAPE 500-1500 J/kg will be in place, although effective bulk shear will be marginal (25-35 knots). Best potential for thunderstorm coverage is expected across the Black Hills given orographic lift where transient supercellular structures/severe weather is possible with the strongest convection through the evening hours.

Active northwest flow is forecast Monday with additional showers and thunderstorms. The best chance for severe weather will be along the theta-e axis focused across southern SD into south-central SD.

Daily chances of showers and thunderstorms persists through Wednesday. A robust upper level ridge will overspread the region by the end of the week into the weekend with much warmer temperatures expected. Current guidance has us on the northeastern periphery of the ridge axis with fairly active northwest flow across the region, resulting in continued chances of storms.

AVIATION

(For the 12Z TAFS Through 12Z Tuesday Morning) Issued At 500 AM MDT Mon Aug 17 2026

VFR conds expected in the period. Isolated TS will be possible today in western SD, esp INVOF the Black Hills. Confidence is too low to add any thunder to KRAP. A shortwave will move through the region this evening and support scattered showers and storms across northeast WY. Added a prob 30 for this to KGCC. Confidence on whether storms will cross the Black Hills remains too low. Thus, left thunder mention out of KRAP this evening.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.